feat: Add hybrid quality evaluation system with CLIP and VLM support

- Add FeatureExtractor for CLIP-based image/text feature extraction
- Add ObjectiveMetricsCalculator for technical quality metrics
- Add VLMEvaluator for vision language model evaluation
- Add HybridQualityGate combining objective + VLM evaluation
- Enhance CharacterMemory with visual feature support
- Add quality optional dependency (torch, ftfy, regex)
- Add unit tests for new modules

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_hybrid_quality_gate.py

@@ -0,0 +1,53 @@
+# Copyright (C) 2025 AIDC-AI
+# Tests for HybridQualityGate
+
+import pytest
+
+from pixelle_video.services.quality.quality_gate import (
+    QualityGate,
+    HybridQualityGate,
+    HybridQualityConfig,
+)
+from pixelle_video.services.quality.models import QualityScore
+
+
+class TestHybridQualityConfig:
+    """Tests for HybridQualityConfig"""
+
+    def test_default_values(self):
+        config = HybridQualityConfig()
+        assert config.enable_clip_score is True
+        assert config.enable_smart_skip is True
+        assert config.smart_skip_threshold == 0.75
+
+    def test_inherits_quality_config(self):
+        config = HybridQualityConfig()
+        assert hasattr(config, "overall_threshold")
+        assert config.overall_threshold == 0.6
+
+
+class TestHybridQualityGate:
+    """Tests for HybridQualityGate"""
+
+    def test_init_default(self):
+        gate = HybridQualityGate()
+        assert gate.hybrid_config is not None
+
+    def test_inherits_quality_gate(self):
+        gate = HybridQualityGate()
+        assert isinstance(gate, QualityGate)
+
+    def test_lazy_load_metrics_calculator(self):
+        gate = HybridQualityGate()
+        calc = gate.metrics_calculator
+        assert calc is not None
+
+    @pytest.mark.asyncio
+    async def test_evaluate_nonexistent_image(self):
+        gate = HybridQualityGate()
+        score = await gate.evaluate_image(
+            "/nonexistent/path.png",
+            "test prompt"
+        )
+        assert score.passed is False
+        assert "not found" in score.issues[0].lower()